Foundation structure

ABSTRACT

The invention provides a method of constructing a composite foundation structure ( 10 ) comprising shuttering ( 12 ) of pre-cast panels ( 14 ), defining an intersecting grid of channels ( 16 ) wherein beams ( 18 ) of settable material are cast. The panels ( 14 ) are connected to form rectangular structures ( 14.1 ). The rectangular structures are arranged on the ground ( 22 ), with the panels ( 14 ) in parallel extending spaced relationship, and with adjacent rectangular structures ( 14.1 ) being connected to and spaced from each other by spacers ( 20 ) of the same material. An interesting grid of channels ( 16 ) is thus defined between the rectangular structures ( 14.1 ). Thereafter a settable material is cast into the channels ( 16 ) and across the rectangular structures ( 14.1 ) and allowed to set. The concrete bonds to the pre-cast panels ( 14 ) and spacers ( 20 ) to form an integral composite foundation structure ( 10 ) that can be constructed relatively easily in problem soils.

This invention relates to a composite foundation structure and a method of constructing such structure.

In certain problem soil conditions, such as sandy, cobbly, clayey, gravely soil or the like, conventional so-called waffle raft foundations are relatively difficult to construct. The reason for this is that when digging a grid of intersecting trenches in such problem soil, the sidewalls of the trenches tend to collapse.

OBJECT OF THE INVENTION

It is accordingly an object of the present invention to provide a composite foundation structure and a method of constructing such structure with which the aforesaid disadvantage can be overcome or at least minimised.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a method of constructing a composite foundation structure including the steps of:

-   -   providing a plurality of panels;     -   arranging the panels to provide shuttering defining a grid of         intersecting channels for receiving settable material;     -   casting settable material into the channels; and     -   allowing the settable material to set and to bond to the         shuttering so that the panels are incorporated into the         foundation structure as an integral part thereof.

The method may include the further step of providing a level surface on which the shuttering is constructed by either levelling the existing soil surface or by removing soil, for example.

The shuttering may be arranged such that they form angular structures defining an internal opening, the grid of channels being defined between adjacent structures.

Adjacent structures may be connected to and spaced from each other with spacers.

The method may include the further step of returning removed soil to the internal openings after the step of arranging the panels and prior to casting the settable material into the channels.

The method may include the further step of compacting the soil in the openings.

The panels may comprise non-degradable pre-cast concrete or fibre reinforced cementicious material.

The spacers may also be of cementicious material.

According to a second aspect of the invention there is provided a composite foundation structure constructed according to the above method.

According to a third aspect of the invention there is provided a foundation structure comprising:

-   -   a grid of intersecting beams of set settable material; and     -   shuttering of pre-cast panels bonded to the settable material.

The shuttering may be of settable material.

Preferably the panels are of non-degradable pre-cast concrete or fibre reinforced cementicious material.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described further by way of example only with reference to the accompanying drawings wherein:

FIG. 1 is a cross-sectional plan view along line B-B¹ in FIG. 2 of a composite foundation structure according to a first embodiment of the invention;

FIG. 2 is a cross-sectional end view along lines A-A¹ in FIG. 1;

FIG. 3 is a cross-sectional end view similar to that of FIG. 2 of a composite foundation structure according to a second embodiment of the invention; and

FIG. 4 is a cross-sectional plan view similar to that of FIG. 1 of a composite foundation structure according to a third embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Referring to FIGS. 1 and 2, a composite foundation structure according to a first embodiment of the invention is generally designated by reference numeral 10.

The foundation structure 10 comprises shuttering 12 of pre-cast panels 14, defining an intersecting grid of channels 16 wherein beams 18 of settable material are cast.

The pre-cast panels 14 are of a fibre-reinforced concrete and are preferably in the form of reject panels of the type used in mining applications, for example. The applicant has found that reject panels are preferable due to their relatively rough surface. The pre-cast panels 14 are nailed to each other to form rectangular structures 14.1 each defining a central opening 14.2.

In use, the ground surface 22 (FIG. 2) is levelled by removing a body of soil and the rectangular structures 14.1 arranged on the ground 22, with the panels 14 in parallel extending spaced relationship, and with adjacent rectangular structures 14.1 being connected to and spaced from each other by spacers 20 of the same material. An intersecting grid of channels 16 is thus defined between the rectangular structures 14.1.

The soil that was removed to level the ground 22 is disposed in the internal openings 14.2 and compacted. Thereafter a settable material in the form of concrete is cast into the channels 16 and across the rectangular structures 14.1 to cover the compacted soil, and allowed to set. The concrete bonds to the pre-cast panels 14 and spacers 20 to form an integral composite foundation structure 10 that can be constructed relatively easily in problem soils.

The method according to the invention provides the further advantage of using waste material that is relatively cheap.

Referring to FIG. 3, a composite foundation structure according to a second embodiment of the invention is generally designated by reference numeral 10A. The foundation structure 10A is similar to the foundation structure 10, with the exception that the pre-cast panels 14A are arranged to provide a channel 16A having an inverted T-shaped cross-sectional or hammer foot profile. Such foundation structure 10A is relatively stiffer but more expensive due to the use of more concrete in the construction thereof. It will be appreciated that the foundation structure 10A according to the second embodiment of the invention is particularly suitable for soil that is very problematic.

Referring to FIG. 4, a composite foundation structure according to a third embodiment of the invention is generally designated by reference numeral 10B. The foundation structure 10B is similar to the foundation structure 10, with the exception that the pre-cast panels 14B are arranged to provide a triangular internal opening 14.2B.

It will be appreciated that variations in detail are possible with a composite foundation structure and a method of constructing such structure according to the invention without departing from the scope of the appended claims. 

1. A method of constructing a composite foundation structure including the steps of: providing a plurality of panels; arranging the panels to provide shuttering defining a grid of intersecting channels for receiving settable material; casting settable material into the channels; and allowing the settable material to set and to bond to the shuttering so that the panels are incorporated into the foundation structure as an integral part thereof.
 2. A method according to claim 1, which includes the further step of providing a level surface on which the shuttering is constructed.
 3. A method according to claim 1 or 2 wherein the shuttering are arranged such that they form angular structures each defining an internal opening, the grid of channels being defined between adjacent structures.
 4. A method according to claim 3 wherein adjacent structures are connected to and spaced from each other with spacers.
 5. A method according to claim 3 or 4 insofar as they are dependant on claim 2 wherein the step of providing a level surface on which the shuttering is constructed includes levelling the existing soil surface, by removing soil, which includes the further step of returning removed soil to the internal openings after the step of arranging the panels and prior to casting the settable material into the channels.
 6. A method according to claim 5, which includes the further step of compacting the soil in the openings.
 7. A method according to any one of the preceding claims wherein the panels are selected from the group comprising non-degradable pre-cast concrete and fibre reinforced cementicious material.
 8. A method according to claim 4 wherein the spacers are of cementicious material.
 9. A method substantially as herein described with reference to the accompanying drawings.
 10. A composite foundation structure constructed according to the method of any one of claims 1 to
 9. 11. A foundation structure comprising a grid of intersecting beams of set settable material and shuttering of pre-cast panels bonded to the settable material.
 12. A foundation structure according to claim 11 wherein the shuttering is of settable material.
 13. A foundation structure according to claim 11 or 12 wherein the panels are selected from the group comprising non-degradable pre-cast concrete and fibre reinforced cementicious material.
 14. A foundation structure substantially as herein described and as illustrated in the accompanying drawings. 